1. Field of the Invention
The present invention relates to a semiconductor device having a gate structure and a method for fabricating the same, and more particularly, to a method for fabricating a semiconductor device having a gate structure, which forms a cutting trench to expose a substrate before forming mandrel patterns, and the semiconductor device formed by the method.
2. Description of the Prior Art
With the trend in the industry being towards scaling down the size of the transistors, non-planar transistor device, such as fin field effect transistor (FinFET) device, has been developed to replace planar transistors to overcome process limits.
The processes of the FinFET device can be integrated with the traditional processes of the logic device, the processes of the FinFET device have good compatibility. More importantly, because the three-dimensional structure of the FinFET device increases the overlapping area between the gate and the fin structure of the silicon substrate, the channel region can therefore be more effectively controlled. This way, the channel region is also longer for an equivalent gate length, and thus the current between the source and the drain is increased.
Although the FinFET device can have more drain current when the size is reduced, some defects in the current FinFET device still exist. For example, the insulating structure of the FinFET device also affects the number of the transistors contained by the whole FinFET device. Hence, how to improve the current FinFET process for resolving this issue has become an important task in this field.